for 2 adults a two wheeled exercise cart is very good, as it is easy to manouver and not too expensive, but make sure it has some sort of springs, so you don't get jolted to death, every bump you go over! It would take 2 adults or one adult and 2 smaller children, you can also get them wider that would take 3 adults. Low entry is great, as you can get in and out quickly, ie if you need to get to your horses head. Make sure it has a swingle tree if you use a breast collar on your horse. A full collar doesnt need one, but with a breast collar, you need the swingle tree so the horse doesnt get rubbed sore on it's chest. Here in uk you sometimes see carts with motorbike wheels or car wheels; don't get a cart that has been made using car wheels. There is too much drag, which makes it harder for the horse to pull, and if you get a puncture in one it can be nasty- sharp swerves to the sides, and a loud noise as it bursts, which can spook your horse, and cause an accident. But there are nice made for the purpose carts available fairly cheaply anyway, just don't be tempted to get a " bargain" with car wheels on it!!